Technical Issues

Most of my technical problems arose because I had decided to forgo using a rendering system I had become accustomed to. That decision was a hard one to make but was worth it as I'll explain later.

The problems arose because of a technique called Adaptive Subdivision. However before I can talk about the particular problem it is important to know that the more complex the mesh is the better the lighting solution it can derrive. However it is not a good idea to have overly complex meshes when trying to do an animation. Therefore Autodesk came up with the good idea of Adaptive subdivison in the radiosity solver.

With Adaptive Subdivision you get the best of both worlds in theory, that being lower complexity meshes combined with areas of mesh detail where there needs to be. In practice though I ran into a lot of problems because of the finer details on some of the models like the venus.

One solution I thought of was to turn the minimum mesh size down but that resulted in really really long calculations in the realm of many hours. This would not do while I was still developing the animation as every change no matter how small would require a full recomputation of the lighting solution.

This led me to use the Filtering and Refining parameters to clean up after the solver. However this really destroyed a lot of the detail on the venus as you can see in the face. It is unfortunate but it was compromise between time I didn't have and quality that I wanted. I believe I was able to strike a fairly good balance between the two. Although it is hard for me to be objective as I've spent a fair bit of time working on this project.

The second technical problem also has to do with the lighting but this time it was the exposure compensation control. Max has five modes with those being Off, Automatic, Linear, Logarthimic, and Pseudo Color. Out of those I focused on the first four as the last was not an appropriate style to be rendering in.

No exposure would require me to change the intensity values of each light to get the desired level of illumination in the scene. However it would also require me to re-process the radiosity solution everytime I changed a light value. This would make fine tuning the image a very tedious process. The solution was to use one of the exposure control mechanisms which use the stored exposure information to allow easy manipulation of brightness, contrast, and exposure value. However it was not without its headaches as I found out.

The problem I had with Logarthimic was that I would need to change the exposure for each frame to get the correct exposure. However this wasn't really a possibility with the way I chose to render to a file. Another problem with Logarthimic was that it seemed to produce very washed out images.

Automatic would adjust the exposure per frame for me but often times it would appear too dark. It was also very sensitive to parameter changes and could easily result in very blown out images in which the screen was mostly pure white. Also since it was automatically adjusting the exposure on a frame by frame basis there was the introduction of flicker related to the inconsistent exposure compensation done by the program.

This left Linear as the choice for me to use. However it was quite tricky to get a balance between over and under exposure. The compromise I ended up with was to go with settings which would produce blown out areas on occasion. I felt this was acceptable as it produced an effect which looked like the camera was compensating for the exposure.